1. Field of the Invention
This invention relates generally to shock absorbers and, more particularly, to a self-pumping hydropneumatic shock absorbing leg or strut with internal level control or regulation for use in motor vehicles. Exemplary of such apparatuses is one having a work cylinder filled with a dampening medium: e.g., oil, under the pressure of at least one gas cushion, such as nitrogen, located in a high pressure chamber which acts as a spring. The work cylinder is divided into two work chambers by a piston supported or carried by a hollow piston rod, which is driven by the movements of the spring and which transports dampening medium from a low pressure chamber into the work chamber connected to the high pressure chamber. The pump cylinder of the piston pump is formed by the hollow piston rod, into which extends a hollow pump rod attached or fastened to the work cylinder and having valve means (e.g., a suction valve) on its forward end. The hole in the pump rod is connected to the low pressure chamber, and with a deregulation opening which can be closed as a function of the position of the work piston in the work cylinder, wherein the deregulation opening connects the work chamber connected with the high pressure chamber with a deregulation passage having a throttle, and emptying into the low pressure chamber.
2. Description of the Prior Art
The prior art includes such shock absorbing legs (German Laid Open Patent Appln. No. 29 44 831, German Patent Publication Published for Opposition Purposes No. 23 56 802), in which the work cylinder is divided into two work chambers by a work piston supported by a piston rod, and in which the work piston is equipped with valves to produce a dampening force. There is a corresponding valve for each direction of movement of the work piston. These valves are used to produce a certain specified dampening force depending on the piston velocity range.